Tread centering mechanism for tire molds



Y April 15, 1952 E. A'. @LYNN 2,593,137

TREAD CENTERING MECHANISM FOR TIRE MOLDS Filed April 17, 1950 2 SHEETS--SHEET l ATTORNEYS E. A. GLYNN TREAD CENTERING MEcHANsM FOR TIRE Moms Filed April 17, 195o vApril 15, 1952 2 sHEETs--SHEET 2 SWW Edwin Glynn wiwi? ATTORNEYS Patented Apr. l5,Y 1952 TREAD 'CENTERING MECHANISM FOR TIRE MQLDS Edwin A. Glynn, Lodi, Calif., assignor to super .Mold Corporation of California, Lodi, Calif., a

corporation of Galifornia .Application April 17, 1950, SerialNo. 156,447

`3 Claims. `1

This .invention `relates .in .general to the art of tire retreading, and inparticular .is directed to" improvements ina tire. retreadingmold.

.A major object of` :this .invention is to provide. a novel mechanism, for a .tire retreading mold, which is operative to assure that the tire-including the .new .tread .portion or camelback thereon-is properly positioned in the mold .before the tread vulcanizing .operation is begun; the purpose .being .to avoid off-center treads; i. e. .a V.new tread which is not straight .and Ytrue about `the tire.

c .Another important object of this .invention is to. lprovide .a tread centering mechanism, .for a tiremold, `.which .comprises V4a novel-assembly of rings positioned on the .mold in amanner to work in -cooperation with .the tire beads. to initially reduce .the 4diameter' f the tire .and permit proper f seating and .alinement .of the. .tread in the. matrix upon closing of the mold, and to .thereafter .per-

mit .of return .of the tire, ywhen inflated y.in the mold.. to. normal diameter.

A furtherobject .of .this `invention is to. provide .a tread .centering mechanism, .as in the preceding paragraph, where-in. the tire bead-engaging rings are .capable .of motion axially. being vspringpressed inwardly but yieldably outwardly; such rings-up.on .closing of the .mold-shifting the tirebeads inwardly or toward .each .other to reduce the tire diameter so 'that the tread may center in the mold, but yielding. outwardly upon inflationof the ytire so that .the latter then returns to normal diameter, .iittng tightly in the mold.

An additional. object of the'invennon is to providea tread .centering mechanism which includes a .novel mount .for attaching the tire bead eneasing .rings to a tire mold.

.It is also an object of the invention to Iprovide a tire centering mechanism. which is designed for easeI and economy .of manufacture.

.Still another object of the invention is to provide a practical .and .reIiable tread centering mechanism and one which will 'be exceedingly effective for the purpose for which lit is designed.

These objects are accomplished by means of such structure and relative :arrangement of partsv as will. fully appear by apex-usal of the following speciiication and claims.

In the drawings:

Fig. 1 is aradial zs'ec'tionoi?` .a tire retreading mold .having `the tread .centering mechanism l .mountedv thereon.

` Fig. 2 is an ele,l ation of one of the tire bead engaging rings and its mount, detached.

Fig. 3 is a. fragmentary radial section showing one of the attachment clip units.

.Referring now .more particularly to the characters of reference .on the drawings, the present invention is .adapted to .be yemployed in connection with .a tire retreading mold .of the type .which includes an .annular body, indicated generally at I, which ,body is .comprised of a pair of initially .separate .mold halves '2 .of annular configuration;

such .mold halves being mounted, by means not hereshown, .for powered opening and closing motionrelative to each other.

The annular mold .body .I .encloses an annular .matrix comprised of matchingmatrix halves 3 secured in corresponding mold halves 2; the. latter each havingva steam .chamber 4 therein for the purpose. .of .heating the .'111Q1d..

Each mold half 2jincludesan inwardly extending skirt :5 formed-.at its inner edge, with an annular strengthening .flange 6; such ange .6..pro-

Vjecting radially .inwardly beyond the adjacent inner edge l ,of the corresponding .matrix half 3. y

The tread centeringv mechanism. which comprises .the present invention, is constructed and mounted on the mo1d,.as.iol1ows:

Each .mold .half .2 is fitted, radially inwardly of its skirt .5., with anv annular mounting plate 8 circumterentially notched, as `at .9, with the corresponding ilange 6 seating .in .such notch; rthe notch opening outwardly so lthat vthe mounting plate 8 is moved into place from inside said mold half.

.Each mounting plate '8 vis rigidly held in place .by a plurality .of circumferentially .spaced attach- .ment .clip units, one of whichis .indicated generally at I0 in Fig.. `3. Eachsuch `attachment clip .unit il) includes .aclip 'II which .spans between the adjacent. mounting plate 8 and flange 6p, and theclip is .held in place by vabolt I2 having .a wing nut I3 threaded thereon.

With the `iloregoing arrangement .each mounting plate 1.8. can be readily .and .conveniently attached to. the mold .half 2 of an existing tire ,retreadingmold.

.Axially .inwardly .of each mounting plate .8 there isdisposed, .in concentric relation, an annular... tire .bead engaging ring i4, and the inner .faces .of Ysaid rings v|14 are .formed with. stag.- .gered .or .radially offset tire. bead receiving seats- 1.5 which extend annularlly about said rings.

At circumferentially spaced points the rings M .are iittedvfith'elongated pins I5 which .pro-

ject outwardly from .said ,rings parallel to the axes. thereof.; such pins .extending 'through elongated bosses 11. formed on the `corresponding mounting plates `8.

Each boss I1 is formed, 'from its inner end. with a relatively deep spring socket I8 and a relatively heavy-duty compression spring I9 seats in said socket inl surrounding relation to the adjacent pin I6 and abuts against the related ring I4. Stop nuts on the outer ends of the pins I 6 limit the extent to which the compression springs I9, which are'. always loaded. may urge the rings I4 axially inward.

For the purpose of illustration, the tire to be retreaded is indicated at 2l; the tire beads at 22; and the new tread material or camelback at 23.

When the tire retreading Irnold is in use with the above described mechanism thereon, the latter functions as follows:

Before the tire, indicated generally at 2|, is placed in the mold, an inside curing bag 24, mounted on a rigid true circle inside curing rim is inserted within the tire casing, the bag 24 then being deiiated. The tire is then placed in the lower half of the mold. The mold halves 2, together with the matrix halves 3, are then closed, by power, from their initially open position. As the mold thus closes, the rings I4 engage the adjacent tire beads 22 and press them toward each other, as-for example-between the full line positions and dotted line positions as in Fig. 1; the tire beads 22 falling into the proper one of the annular seats I5. The movement of the tire beads toward each other has the effect of pulling the tire side walls uniformly about the outer edges of the true circle curing g rim 25 so as to reduce the diameter of the tire I so that it freely engages in the mold and may assume a correct seat therein, with the new tread material or camelback'23 properly positioned or centered in the matrix.

After closing of the mold the curing bag 24 is inilated. With this inflation of the curing bag the tire 2I is caused to reassume its normal diameter, positively forcing the new tread material or Camelback 23 in proper position into the matrix comprised of the matrix halves 3, and at the same time the tire beads 22 are forced apart and returned to substantially their normal position. As the tire beads 22 are thus first pulled together and then forced apart, the tire bead engaging -rings I4 are correspondingly shifted axially first inwardly and then outwardly while held in proper centered position both radially and axially of the mold. When moving outwardly, they-are guided by the pins I6 and move against the compression of the springs I9. As a result the tire beads 22, during the following tread vulcanizing process, are maintained alined in directions both axially and radially of the mold; thus assuring that the tire 2I must remain in the mold in such position that the new tread is properly centered and cured straight and true on the tread of the tire.

The tread centering mechanism, as described herein, is of particular advantage for use in connection with the retreading of low pressure type balloon tires which are characterized by sidewalls which are extremely iiexible. This flexibility makes it difficult to properly position a w tire in the mold without the tread centering seen that there has been produced such a device as substantially fuliills the objects of the invention as set forth herein.

While this specification sets forth in detail the present and preferred construction of the device, still in practice such deviations from such detail may be resorted to as do not form a departure from the spirit of the invention, as defined by the appended claims.

Having thus described the invention, the following is claimed as new and useful, and upon which Letters Patent are desired:

l. Afull-circle tire mold including a body and a matrix therein; the body and matrix terminating radially out from the beads of a tire to be confined in the mold; a tread centering device comprising a pair of axially alined and separated rings having annular tire-bead engaging seats, the rings being disposed radially and laterally inward from the body and matrix and clear of the same, means supporting the rings from the body concentric with the axis thereof and for movement in a direction axially of the mold, and spring means yieldably urging the rings toward each other.

2. A full-circle tire mold including a body and a matrix therein; the body and matrix terminating radially out from the beads of a tire. to be confined in the mold; a tread centering device comprising a pair of axially alined and separated rings having annular tire-bead engaging seats, the rings being disposed radially and laterally inward from the body and matrix and clear of the same, ring-like mounting plates engaging and supported from the body at its radially inner termination, pins secured in the rings parallel to the axis thereof and slidably supported in the plates, and compression springs between the plates and rings.

3. A full-circle mold including a body and a matrix therein; the body and matrix terminat- `ing radially out from the beads of a tire to be confined in the mold; a tread centering device comprising a pair of axially alined and separated rings having annular tire-bead engaging seats, the rings being disposed radially and laterally Vinward from the body and matrix and clear of REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,989,634 Iverson Jan. 29, 1935 FOREIGN PATENTS Number Country Y Date 30,774 Australia June 29, 1931 of 1930 

